[PATCH 4.9 77/78] ext4: fix leaking sysfs kobject after failed mount

[Greg Kroah-Hartman]

From: Eric Biggers <ebiggers@xxxxxxxxxx>

commit cb8d53d2c97369029cc638c9274ac7be0a316c75 upstream.

ext4_unregister_sysfs() only deletes the kobject.  The reference to it
needs to be put separately, like ext4_put_super() does.

This addresses the syzbot report
"memory leak in kobject_set_name_vargs (3)"
(https://syzkaller.appspot.com/bug?extid=9f864abad79fae7c17e1).

Reported-by: syzbot+9f864abad79fae7c17e1@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 72ba74508b28 ("ext4: release sysfs kobject when failing to enable quotas on mount")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200922162456.93657-1-ebiggers@xxxxxxxxxx
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/ext4/super.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4336,6 +4336,7 @@ cantfind_ext4:
 #ifdef CONFIG_QUOTA
 failed_mount8:
 	ext4_unregister_sysfs(sb);
+	kobject_put(&sbi->s_kobj);
 #endif
 failed_mount7:
 	ext4_unregister_li_request(sb);